State-Variable Public Goods and Social Comparisons over Time

The optimal provision of a state-variable public good, where the global climate is the prime example, is analyzed in a model where people care about their relative consumption. We consider both keeping-up-with-the-Joneses preferences (where people compare their own current consumption with others’ current consumption) and catching-up-with-the-Joneses preferences (where people compare their own current consumption with others’ past consumption) in an economy with two productivity types, overlapping generations and optimal nonlinear income taxation. The extent to which the conventional rules for public provision ought to be modified is shown to depend on the strength of such relative concerns, but also on the preference elicitation format.